Effects of Curing Temperature on Expansion of Concrete Due to ASR

TL;DR

This study examines how different curing temperatures affect concrete expansion caused by alkali-silica reaction (ASR), finding that higher temperatures initially speed up expansion but later slow it down.

Contribution

The study identifies the temperature-dependent behavior of ASR expansion and suggests optimal curing temperatures for predictive modeling.

Findings

Concrete prisms cured at 50 °C or 60 °C showed the highest expansions during the experimental period.

Higher temperatures (70 °C and 80 °C) initially caused rapid expansion but slowed down later.

Decreased [OH−] levels, due to reaction and temperature effects, significantly influence ASR expansion.

Abstract

In the laboratory study of alkali–silica reaction (ASR), models attempt to predict the service life of concrete due to ASR by correlating the performance of concrete at high and low temperatures. However, the consequences of elevating temperature are not so encouraging. In this paper, the influence of temperature on the expansion of 2-graded concrete and 3-graded concrete caused by ASR was investigated by curing the concrete under different temperatures ranging from 40 °C to 80 °C. Increased temperature resulted in rapid expansion at the early stages, but the expansion rate of concrete prisms cured at the higher temperatures (70 °C and 80 °C) was slowed down at the later stages, and concrete prisms cured at 50 °C or 60 °C showed the highest expansions during the experimental period. The chemical analysis results of the pore solution expressed from the concrete show that the ASR expansion is significantly influenced by the [OH−]: the decrease in [OH−] leads to the retardation of the ASR expansion. The decrease in [OH−] is attributed to the consumption of OH− ions for the alkali–silica reaction and the decrease in activity of NaOH(aq) influenced by the temperature. For large cross-section specimens, the OH− within the concrete for alkali–silica reactions cannot be effectively compensated by the external alkali solution. In the accelerated test to evaluate ASR for large cross-section specimens, a curing temperature of less than 60 °C is suggested. This study provides critical insights into the temperature dependency of ASR expansion of concrete, offering a curing temperature range for developing predictive models of ASR expansion under varied environmental conditions.

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